This renewal builds on the progress in current funding. ADAM10 was shown to be quite important in humoral immune function. Mice in which their B cells lack ADAM10 (ADAM10B-/-) had defective lymphoid architecture. We will examine whether multiple antigen injections can overcome the defects seen. Newly data indicates that B cell TNF production is responsible for the altered germinal center architecture seen in the ADAM10B-/- mice and that this is due to increased expression of the TNF sheddase ADAM17. The opposite effects for ADAM10 will also be examined, namely what happens when ADAM10 is overexpressed in B cells. Early overexpression in hematopoietic stem cells was shown to block B cell production in the current funding period. Incorporation of a floxxed stop site in fron of the ADAM10 will allow delay of the overexpression until B cells develop. In addition, the ADAM17B-/- mouse should also have elevated ADAM10 expression and enhanced Ig production. Of particular interest is IgE production and we hypothesize that elevated IgE production will correlate with elevated B cell ADAM10. With respect to ADAM10 targets important in B cell function, based on preliminary data, we will concentrate on two substrates, CD23 and fractalkine. Finally, we will examine whether B cell exosomes play a role in the immunostimulatory activity of IgE-antigen complexes. In the second aim, mice with elevated B cell ADAM10 will be examined for enhanced lung inflammation in mouse asthma models and the effect of ADAM10 inhibitors will be examined to determine if this mechanism is solely ADAM10 related. The effect of ADAM10 inhibitors on the lymphoid architecture of the bronchial associated lymphoid tissues will be determined. Using IgE reporter mice, we will specifically determine the effect of ADAM10 inhibitors and ADAM10B-/- mice for germinal center and IgE plasma cell levels. We anticipate that when ADAM10 levels are inhibited we can specifically inhibit the IgE response. Using a model we have developed for suppression of an ongoing asthma response, ADAM10 inhibitors will be examined for their capacity to block this response. Mice lacking ADAM10 in their epithelial cells will be studied to determine whether ADAM10 inhibitors are working primarily by their effect on immune cells. Preliminary evidence indicates that a subpopulation of active allergic patients have elevated B cell ADAM10 levels when compared to controls. We will examine if the B cells from these patients have enhanced IgE production, using in vitro B cell stimulation models. Overall, the project will continue studies ino new promising avenues for understanding and harnessing ADAM10 to control the immune response. In addition, these two aims test the hypothesis that the ratio of ADAM10 to ADAM17 is important especially with respect to the allergic phenotype.